JPH0778466B2 - Method for measuring uniaxial compressive strength of cement solidified body - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for measuring the uniaxial compressive strength of a cement-solidified body for estimating the uniaxial compressive strength of a low-level radioactive cement-solidified body housed inside a drum or the like. .

[Prior Art] In general, waste discharged from a nuclear power plant or the like is stored in a container such as a drum can after being solidified with cement. A plurality of inspections are performed on the cement solidified body stored in the drum can to confirm whether or not it meets the technical standards (disposal confirmation items) defined by law. Then, the cement solidified bodies that have passed all the technical standards are sent to the low-level radioactive waste storage center and disposed of in the ground.

By the way, in a plurality of inspections on the cement solidified body,
When examining the uniaxial compressive strength of a cement-solidified body, application of the ultrasonic wave propagation velocity method is being considered. This method
By remote control, insert a transmitter and receiver at opposite positions by sandwiching the drum containing the solidified cement.
The ultrasonic wave transmitted from the transmitter is received by the receiver, and the propagation velocity of the ultrasonic wave passing through the cement-solidified body is measured. Then, the uniaxial compressive strength of the cement-solidified body is estimated based on the correlation between the uniaxial compressive strength and the ultrasonic wave propagation velocity obtained in advance.

[Problems to be Solved by the Invention] However, in the uniaxial compressive strength inspection of the cement solidified body by the ultrasonic propagation velocity method, it is necessary to bring a plurality of measuring elements (transmitter and receiver) into close contact with the surface of the drum can by remote control. For that reason, crimping equipment is required, and the inspection device requires a lot of trouble.

Further, there is a problem that the inspection efficiency is poor because it cannot be performed simultaneously with other inspections.

The present invention is intended to solve the above problems.

[Means for Solving the Problems] In the method for measuring the uniaxial compressive strength of a solidified cement according to the present invention, first, the density of the solidified cement is calculated, and the uniaxial compressive strength of the solidified cement is estimated based on the calculation result. It is characterized by that.

As a result of diligent research, the present inventors have found that the density of the cement solidified body is correlated with the uniaxial compressive strength of the cement solidified body. Accordingly, the present invention is to estimate the compressive strength by calculating the density of the cement solidified product by the management data of the cement solidified product or other method without using a special method and a plurality of devices. .

[Operation] According to the uniaxial compressive strength measuring method of the cement solidified product of the present invention, the uniaxial compressive strength of the cement solidified product is estimated based on the measurement result by measuring the density of the cement solidified product. As the method for obtaining the density of the solidified cement, it may be used if it can be known directly from the management data of the solidified cement, or may be obtained by another inspection method.

[Example] The discovery as the principle of the uniaxial compressive strength measuring method of the cement solidified product of the present invention will be described with reference to FIG.

FIG. 1 shows the relationship between the density and the uniaxial compressive strength of the cement solidified body in which the horizontal axis represents the density of the cement solidified body and the vertical axis represents the uniaxial compressive strength of the cement solidified body. As can be seen in this figure, a linear correlation is obtained with the various cement materials used, and it can be determined that the uniaxial compressive strength increases as the density of the cement solidified body increases. Thus, the uniaxial compressive strength of the cement solidified product can be easily estimated by obtaining the density of the cement solidified product.

Here, as a method of measuring the density of the solidified cement, a method of measuring the density by using quality control data of the solidified cement, and measuring the density by actually measuring the volume and weight of the solidified cement It is possible to do this.

First, a method of measuring the density by using the quality control data of the cement solidified product will be described.

Among the quality control data of various solidified cements, the present inventors have focused on the relationship between the mixture ratio (cement / waste liquid ratio) of the cement and the radioactive waste liquid constituting the solidified cement and the density of the solidified cement. did. That is, as a result of analyzing various data, it was found that the density of the cement solidified product increased as the cement / waste liquid ratio increased. Thereby, the reference data of the cement / waste liquid ratio and the density of the solidified cement is prepared in advance, and from the cement / waste liquid ratio when the solidified cement is produced, the density of the solidified cement is estimated from the reference data, The uniaxial compressive strength of the cement solidified product is estimated from the correlation table between the density of the cement solidified product and the uniaxial compressive strength shown in FIG.

In this way, the density of the cement solidified product can be estimated only by examining the cement / waste liquid ratio in the quality control data of the cement solidified product, and the uniaxial compressive strength of the cement solidified product can be easily obtained without using a device. Can be estimated.

Next, a method of actually measuring the volume and weight of the cement solidified product to calculate the density will be described. The weight of the solidified cement in the drum can is measured by an automatic scale or the like.

The cement solidified body filled inside the drum can is not filled up to the upper end of the drum can because the waste treatment is performed by remote control, and there is some space above the drum can. Therefore, the height from the bottom surface of the solidified cement body to the boundary surface between the space and the solidified cement body (hereinafter, solidified body interface height) is measured, and the volume is calculated from the solidified body interface height and the known drum can inner diameter. Then, the density of the solidified cement product can be calculated based on the measured weight.

As a method of measuring the volume of the solidified cement, a method of measuring the volume by calculating the solidified body interface height by measuring the space of the solidified cement from the upper end of the drum in the state where the upper part is open, is sealed. In the case of a drum, a method of measuring the volume of the cement-solidified body in the same manner by using a device provided with a stylus around the drum can be considered.

The method of measuring the volume of the solidified cement from the drum with the top open is to remotely measure the height of the space from the top of the opened drum with a scale, etc., and then determine the height of the solid interface. It is a method of calculating the volume from a known drum inner diameter.

Then, the density of the cement solidified product can be easily calculated from the weight and volume of the cement solidified product measured in advance.

On the other hand, as a method for measuring the volume of the cement-solidified body using an apparatus in which a measuring element is provided around a sealed drum can, the methods shown in FIGS. 2 and 3 can be considered.

The apparatus shown in FIG. 2 has a drum can 2 mounted on an automatic balance 1 on which a drum can 2 is placed and which is vertically movable.
A gamma ray source 5 and a gamma ray detector 6 which are attached to a fixing member (not shown) with a slit plate 4 interposed are provided at positions facing each other.

Then, the elevating table 3 is moved up and down to pass the drum can 2 vertically between the gamma ray source 5 and the gamma ray detector 6, and gamma rays from the gamma ray source 5 are passed through the slits 4a of the slit plate 4 to the drum can 2. The solidified body interface height L can be detected by irradiating the solidified body and irradiating the solidified body with the space 7 inside the drum 2 and the change in the transmittance of gamma rays between the cement solidified body 8 and the gamma ray detector 6. .
Then, the volume is calculated from the height L of the solidified body interface and the known inner diameter of the drum 2.

With this, the density of the cement solidified product is calculated with high accuracy and speed, and the uniaxial compressive strength of the cement solidified product is estimated from the correspondence table between the density of the cement solidified product and the uniaxial compression density shown in FIG. be able to.

Further, if a mechanism for detecting the solidified body interface height L is added to a part of the radioactivity concentration test for measuring the radioactivity concentration of the solidified cement, the comprehensive inspection of the solidified cement can be simplified and shortened. It can be used for evaluation of homogeneity of the solidified cement product.

In the apparatus shown in FIG. 3, a drum 2 is placed via an automatic scale 10, an elevating table 11 that is vertically movable and axially rotatable, and a radiation dose gauge 12 on the side of the drum. It is a thing.

Then, by raising and lowering the drum can 2 by means of the lift table 11 and scanning the dosimeter 12 over the entire surface of the drum can, the change in the dose rate between the space portion 7 and the inside of the cement solidified body 8 is measured. Thus, the height L of the solidified body interface can be detected. The volume is calculated from this solidified body interface height L and the known inner diameter of the drum 2, and the density is calculated by measuring the weight of the cemented solidified body 8 with the automatic balance 10.

As a result, it is possible to obtain the same effects as those of the device shown in FIG.

Incidentally, using the conventional ultrasonic propagation velocity method, the solidified body interface height is detected by a change in the ultrasonic propagation velocity, even if the density of the cement solidified body is obtained thereby, the same effect as the above example Can be obtained.

[Effects of the Invention] As described above, according to the method for measuring the uniaxial compressive strength of the cement-solidified body of the present invention, attention is paid to the correlation between the density of the cement-solidified body and the uniaxial compressive strength of the cement-solidified body. However, the density of the cement solidified body is measured from the management data of the cement solidified body or the inspection method other than the uniaxial compressive strength inspection, and the cement solidification is easily and quickly performed without using a special method or a complicated device. The uniaxial compressive strength of the body can be estimated.

Further, it is possible to simplify the inspection of the solidified cement and shorten the inspection time.

[Brief description of drawings]

1 to 3 show an embodiment of the method for measuring the uniaxial compressive strength of the cement solidified product of the present invention, and FIG. 1 shows the correlation between the density of the cement solidified product and the uniaxial compressive strength. FIG. 3 and FIG. 3 are schematic diagrams showing an apparatus for measuring the volume of a cement solidified body. 1,10 …… Automatic scale, 2 …… Drums, 3,12 …… Lift, 4
...... Slit plate, 5 ...... Gamma ray source, 6 ...... Gamma ray detector, 7 ...... Space inside the drum can, 8 ...... Cement solidified material, L ...... Solidified body interface height (space inside drum can and cement Boundary with solidified body).

Claims (1)

[Claims] 1. A method for measuring the uniaxial compressive strength of a cement-solidified body stored in a container such as a drum, which comprises first calculating the density of the cement-solidified body and then calculating the uniaxial compressive strength of the cement-solidified body. A method for measuring the uniaxial compressive strength of a cement solidified body, which comprises estimating the uniaxial compressive strength of the cement solidified body based on the results.